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<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Dear gmsh
users,</SPAN><?xml:namespace prefix = o ns =
"urn:schemas-microsoft-com:office:office" /><o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><FONT
face="Times New Roman"> <o:p></o:p></FONT></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">I have recently started to use gmsh
for my purposes (radiation transport). I encounter the following rather general
issue: My own FEM code reads a mesh file with the internal element information
and boundary element information consisting of a list of host internal element
and its face that makes up the boundary. From the latter I can then extract the
unit normal and compute the required integrals. I therefore need to convert the
mesh file from gmsh to my own format.<o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">In the gmsh format the boundary
elements are listed (if <SPAN class=206031113-08072008>needed</SPAN>) with
the associated nodes. I could of course easily search the Element list to see to
what elements the boundary elements belong and which face it is but this seems
an expensive operation (work scales with the square of the mesh size I suppose).
<o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">It seems to me you always need to
find the host element to figure out the unit normal as the sign of it is
otherwise unknown. Is this the proper way of doing things or is there a cleverer
alternative?</SPAN><o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><FONT
face="Times New Roman"> <o:p></o:p></FONT></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Thanks and best
regards.<o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Danny
Lathouwers.</SPAN><o:p></o:p></P></SPAN></FONT></DIV></BODY></HTML>